What are the ISO standards for cleanrooms?

ISO 14644-1 and ISO 14644-2 are the ISO standards for cleanrooms. They deal with particle size and particle count, establishing a cleanroom rating of ISO 1-9 based on those factors. Cleanroom users and engineers will typically refer to a room as an 'ISO 4,' 'ISO 5,' and so on.

What are the limitations of ISO cleanroom measurements?

ISO cleanroom measurements require less information about the cleanroom than Federal Standard 209 did, and allow for fewer tester locations for cleanliness. The ISO standards establish 0.1 micron as the standard particle diameter, create three new cleanliness classes, and aren’t as concerned with airflow velocity, room pressure, room temperature, and the distance from the floor or the filter face when taking an air sample for a particle count. This variability can lead to fluctuations in particulate levels and thus, in ISO classifications.

What should be kept in mind when testing cleanrooms?

It’s important to be aware of at what state testing was done: at rest, as built, or in operation, and to keep all factors in mind.

ISO Cleanroom Standards Explained: ISO Classes 1–9

Posted by Liberty Industries on April 15, 2026 9:30 am | Comments Off

Understanding ISO cleanroom classifications is essential when specifying, designing, or evaluating controlled environments. Classifications such as ISO 7 and ISO 8 directly impact product quality, regulatory compliance, and operating costs.

Cleanroom classifications, such as ISO 7 and ISO 8, have direct implications for product quality, compliance, and operating costs. The following overview explains ISO 1 through ISO 9 classifications, typical applications, and the equipment required to support each environment.

Introduction to ISO Classes

ISO cleanroom standards are defined in ISO 14644-1, which classifies cleanrooms by airborne particle concentration per cubic meter of air. These ISO classifications range from ISO 1, the cleanest environment with the strictest particle limits, to ISO 9, which is comparable to typical indoor air.

An ISO cleanroom is classified by the maximum allowable particle count at defined particle sizes, most commonly 0.1 µm, 0.2 µm, 0.3 µm, 0.5 µm, and 5.0 µm. The lower the ISO class number, the fewer particles permitted and the cleaner the environment.

Understanding ISO cleanroom standards is critical when specifying HVAC systems, air changes per hour, filtration levels, gowning procedures, and cleaning protocols. A mismatch between your process and your ISO classification can lead to contamination risks, audit findings, and unnecessary capital expense.

For example:

ISO 1 cleanroom environments enable extremely low particle concentrations and are used in advanced research and nanotechnology.
ISO 8 cleanrooms allow higher particle counts and are common in medical device assembly and certain pharmaceutical processes.

Key Benefits of ISO Cleanroom Classifications

Cleanroom equipment, apparel, and contamination-control products must align with ISO cleanroom standards to meet regulatory and operational requirements across multiple industries.

Regulatory compliance. Regulatory compliance with standards such as FDA and GMP requirements.
Product protection. Reduced contamination risk in sensitive processes.
Process stability. Consistent environmental control, including airflow and filtration.
Risk mitigation. Reduced risk of rework, scrap, and recalls.
Scalable design. Ability to size cleanrooms based on process requirements.

Use Cases For Each ISO Class

Below is a practical overview of ISO 1 through ISO 9 cleanrooms and the typical applications of each classification.

ISO 1 Cleanrooms

ISO 1 cleanroom environments represent the highest level of air cleanliness defined by ISO classifications. These environments require ultra-high-efficiency filtration, tightly controlled airflow, and strict gowning protocols. Equipment used in ISO 1 cleanrooms must generate minimal particulates and meet stringent material-compatibility requirements.

In ISO 1 cleanrooms, particle concentrations are extremely limited, which means these spaces are suitable for tasks like:

Advanced nanotechnology research
Quantum computing component development
Specialized semiconductor processes

ISO 2 Cleanrooms

ISO 2 cleanrooms support processes that require a near-zero risk of contamination. At this level, facility design must account for vibration control, material off-gassing, and micro-contamination control in addition to airborne particles.

Typical applications include:

Precision optics manufacturing
High-end semiconductor fabrication
Aerospace component research

ISO 3 Cleanrooms

ISO 3 environments are used in semiconductor and microelectronics manufacturing. Maintaining compliance requires strict gowning procedures and controlled equipment placement.

These cleanrooms often feature:

Laminar airflow systems
High air change rates
Strict personnel entry protocols

ISO 4 Cleanrooms

ISO 4 cleanrooms maintain low particle counts and are used in a range of industrial applications. These spaces typically use HEPA or ULPA filtration and high air change rates to control airborne contamination.

Applications may include:

Microelectronics assembly
Sensitive optical component production
Advanced research laboratories

ISO 5 Cleanrooms

ISO 5 cleanrooms use laminar airflow hoods or cleanroom modules to control particle levels at critical locations. Defined gowning procedures and environmental monitoring are required to maintain compliance.

They are often found in:

Aseptic pharmaceutical filling operations
Sterile compounding pharmacies
Biotechnology research labs
Semiconductor manufacturing zones

ISO 6 Cleanrooms

ISO 6 cleanrooms are used as transitional spaces between higher and lower stringency areas. Facilities may combine ISO 6 and ISO 5 zones for specific process needs. Equipment and furnishings must support contamination control and daily operational requirements.

Common uses include:

Medical device manufacturing
Pharmaceutical support spaces
Electronics assembly

ISO 7 Cleanrooms

ISO 7 cleanrooms are commonly specified in industrial and pharmaceutical settings. Routine environmental control includes scheduled cleaning, approved disinfectants, and validated procedures. Personnel follow documented gowning and entry protocols specific to ISO 7.

Typical use cases include:

Medical device assembly
Pharmaceutical manufacturing support areas
Electronics manufacturing
Aerospace component assembly

ISO 8 Cleanrooms

ISO 8 cleanrooms permit higher particle counts than ISO 7 and are used in regulated industries that require basic contamination control. Gowning and entry procedures are less restrictive but still defined. Typical attire includes hair covers, lab coats or coveralls, gloves, and shoe covers.

Applications include:

Medical device packaging
Nutraceutical production
Certain pharmaceutical processing areas
Component assembly

ISO 9 Cleanrooms

ISO 9 environments are the least restrictive ISO classification and are similar to standard indoor air. ISO 9 may serve as a baseline before adding filtration and airflow control for higher classifications.

While they are not typically considered “cleanrooms” in the traditional sense, ISO 9 classifications can apply to applications like:

Controlled warehouse environments
General manufacturing spaces with minimal contamination risk

How Liberty Industries Supports ISO Cleanroom Standards

Meeting ISO cleanroom standards requires compatible equipment, furnishings, and contamination control products. Liberty Industries supplies cleanroom equipment and consumables designed to support ISO classifications from ISO 1 through ISO 8.

Cleanroom solutions are available to support ISO classifications from ISO 1 through ISO 8, including:

Cleanroom apparel and gowning systems
Gloves, wipes, and cleaning supplies
Cleanroom furniture, pass-throughs, and accessories
Environmental monitoring and airflow support equipment

Product selection should align with cleanroom classification, regulatory requirements, and operational objectives.

Build With Confidence

Selecting the appropriate ISO cleanroom classification impacts compliance, product quality, and operating costs. Understanding ISO classes supports facility design aligned with process requirements and cost control.

For questions about cleanroom classification or facility requirements, consult with a cleanroom specialist to ensure compliance and operational efficiency.